I saw The SimpsonsViva Ned Flanders episode over the weekend and was surprised to find The Moody Blues in it ~ I always wanted to know what was inside Ray Thomas' flute, now I know it conceals a dagger.

Honorable mention of The Seeds on The Mothers-In-Law, Mel Torme on Night Court, and Fabian literally singing Turn Me Loose to a fanatical Laverne and Shirley. (though, the last two were individual artists so I don't know if they count)

Never been a fan of Korn, nor have I paid much attention to South Park after the first couple of seasons, but I loved the halloween episode, "Korn's Groovy Pirate Ghost Mystery." Great Scooby Doo parody, and a really weird thing to do with the guest stars. Plus, it was a funny episode in general.